Biological variation of cardiovascular risk factors in patients with diabetes

Biological variation refers to the natural fluctuations found when repeated measurements are made in a biological system. Generally, biological variation remains within narrow boundaries in health, but may differ in pathological states, with implications for the diagnosis and monitoring of disease processes. In disease, biological variation may alter such that any subsequent measurement may need to have a greater difference compared with a healthy control to be biologically relevant. Treatments such as insulin or anti‐hypertensive therapy have been shown to reduce biological variability closer to normal levels and theoretically this may help prevent complication development or progression in conditions such as diabetes. This article reviews how biological variation can influence our identification and assessment of vascular risk factors in a person with diabetes. The role of biological variation in the diagnosis of diabetes (glucose and HbA_1c) is then examined. Finally, the influence that common treatments in diabetes have in modifying biological variation is described.     

Birth plans—Impact on mode of delivery,obstetrical interventions,and birth experience satisfaction: A prospective cohort study

Objective

To examine whether the presence of a birth plan was associated with mode of delivery, obstetrical interventions, and patient satisfaction.

Methods

This was a prospective cohort study of singleton pregnancies greater than 34 weeks’ gestation powered to evaluate a difference in mode of delivery. Maternal characteristics, antenatal factors, neonatal characteristics, and patient satisfaction measures were compared between groups. Differences between groups were analyzed using chi‐squared for categorical variables, Fisher exact test for dichotomous variables, and Wilcoxon rank sum test for continuous or ordinal variables.

Results

Three hundred women were recruited: 143 (48%) had a birth plan. There was no significant difference in the risk of cesarean delivery for women with a birth plan compared with those without a birth plan (21% vs 16%, adjusted odds ratio [adjOR] 1.11 [95% confidence interval (CI) 0.61‐2.04]). Women with a birth plan were 28% less likely to receive oxytocin (P < .01), 29% less likely to undergo artificial rupture of membranes (P < .01), and 31% less likely to have an epidural (P < .01). There was no difference in the length of labor (P = .12). Women with a birth plan were less satisfied (P < .01) and felt less in control (P < .01) of their birth experience than those without a birth plan.

Conclusion

Women with and without a birth plan had similar odds of cesarean delivery. Though they had fewer obstetrical interventions, they were less satisfied with their birth experience, compared with women without birth plans. Further research is needed to understand how to improve childbirth‐related patient satisfaction.     

Effect of anaesthesia on the negative feedback action of gonadal steroids on gonadotrophin secretion in the ovariectomized guinea-pig

The effects of urethane or sodium pentobarbitone anaesthesia on the feedback effects of oestradiol or progesterone on gonadotrophin secretion in the ovariectomized guinea-pig have been investigated. In the control experiments in which no steroids or vehicles were given the concentration of LH and FSH in samples of peripheral blood collected at intervals of 15 min varied in a random episodic manner. The mean level of LH was significantly greater in sodium pentobarbitone- and urethane-anaesthetized animals when compared with conscious animals, and in the conscious animals there was a progressive fall in mean LH level during the course of serial sampling. This effect was not observed in anaesthetized animals. Oestradiol benzoate (2 microgram s.c.) inhibited LH secretion in conscious animals and in those anaesthetized with sodium pentobarbitone, but not in urethane-anaesthetized guinea-pigs. Progesterone (200 microgram s.c.) progressively depressed plasma LH levels in conscious and urethane-anaesthetized animals, but not in guinea-pigs anaesthetized with sodium pentobarbitone. The effect of anaesthesia was the converse of that observed with oestradiol treatment. Significant changes in FSH secretion were not observed under any experimental conditions. These findings point to the existence of a mechanism in spayed guinea-pigs that restrains LH secretion, the action of which is reduced by anaesthesia and modified by oestradiol and progesterone.     

The relationship of human platelet density to platelet age: platelet population labeling by monoamine oxidase inhibition

The relationship between platelet density and platelet age appears to vary between species with relatively few labeling studies in humans reported. In this study, irreversible monoamine oxidase (MAO) inhibitors were used to biochemically label the circulating platelet population in 15 humans. Platelet samples were then isolated during the 15 days after drug ingestion. The platelets were separated by density on continuous linear Percoll gradients and the density distributions were divided into five fractions containing approximately equal numbers of platelets. Baseline MAO activity was strongly correlated with platelet density. Twenty-four hours after a single dose of tranylcypromine, platelet MAO activities in the density subpopulations were reduced to 14% to 17% of the baseline values. During the first five days after inhibition, the rates of recovery of MAO activity (percentage per day) were inversely proportional to platelet density. The recovery rates in the two most dense fractions were initially slow but increased after five days. Percentage recovery of MAO activity in the least dense fraction was significantly greater than the percentage recovery in the most dense fraction on days 2, 3, 5, and 8 (P less than .01, sign test). These results support the hypothesis that normal human platelets show a small increase in density with age, but they do not exclude the additional possibility that human platelet lifespan is positively correlated with platelet density.